Low-loss Dielectric Materials Microwave Performance Testing

Though dielectric materials was discovered since last century, many problems about such kind of complex permittivity still left for research. The topic of this paper is to measure the low waste materials so the resonance method is employed. The merits of this method are high measurement sensitivity, exact measurement result and the result of the waste can reach 10?4 , which is barely achieved by using other methods. Then in this article resonance method is adopted.The paper analyzes the usual measurement methods of complex permittivity, then analyzes and chooses TE0np circular cavity based on the methods of the TE01n high-Q circular cavity, uses the mode purifying and cavity dimension optimizing techniques. The resonant frequencies of varies modes in the resonant cavity have been drawn by using MATLAB software, which makes our work more rapid and convenient. The paper then designs the broadband multimode test cavity and solves the problem of mode identifying automatically and mode searching in the test of low loss dielectric material. The testing system which consists of the Synthesized Sweeper, Scalar Network Analyzer, testing set, detector and the computer has been established to test the low-loss dielectric materials'complex permittivity. At the same time the automatic test procedure that controlled the Synthesized Sweeper and the Scalar Network Analyzer with VB have been written out. Finally some samples of dielectric are tested by the testing set. This test system is convenient, highly automatic, rapid and exact. The test method of thin film is analyzed, which widens the using range of this test system.So, the test technique can be used for the automatic, rapid, accurate, broad-band and measurement of material parameters of low-loss dielectric materials, and it is very practical.